Status Update of the MAJORANA DEMONSTRATOR Neutrinoless Double Beta Decay Experiment

TL;DR

The Majorana Demonstrator aims to establish the feasibility of a large-scale neutrinoless double beta decay experiment using high purity Germanium detectors, with low background levels and modular design, to explore fundamental neutrino properties.

Contribution

This paper reports the current status and progress of constructing and commissioning the Majorana Demonstrator, a novel low-background, modular Germanium detector array for neutrinoless double beta decay searches.

Findings

Construction and commissioning are underway at Sanford Underground Research Facility.

The experiment has started data collection with enriched detectors.

Projected background level is less than 3 counts per tonne-year.

Abstract

Neutrinoless double beta decay searches play a major role in determining neutrino properties, in particular the Majorana or Dirac nature of the neutrino and the absolute scale of the neutrino mass. The consequences of these searches go beyond neutrino physics, with implications for Grand Unification and leptogenesis. The \textsc{Majorana} Collaboration is assembling a low-background array of high purity Germanium (HPGe) detectors to search for neutrinoless double-beta decay in $^{76}$Ge. The \textsc{Majorana Demonstrator}, which is currently being constructed and commissioned at the Sanford Underground Research Facility in Lead, South Dakota, will contain 44 kg (30 kg enriched in $^{76}$Ge) of HPGe detectors. Its primary goal is to demonstrate the scalability and background required for a tonne-scale Ge experiment. This is accomplished via a modular design and projected background of less than 3 cnts/tonne-yr in the region of interest. The experiment is currently taking data with the first of its enriched detectors.